SCUBA and freedivers face a variety of dangers associated with these sporting activities. One such danger is decompression sickness that results from inert gas uptake during a dive. The amount of inert gas uptake is affected by the depth/pressure experienced over time by the diver. Dive computers have been used that employ diving decompression algorithms that track depth and time in order to determine dive stops in order to help avoid the danger of decompression sickness.
Further, physiological data from the diver can provide improved information to be utilized by the diving algorithm operating on a dive computer that determines dive time and decompression stop times and depth. For instance, the ZHL-8ADT model uses workload from a diver's heart rate to improve the diving algorithm. An example of a dive computer that utilizes heart rate information to improve a dive algorithm is found in U.S. Pat. No. 7,310,549 entitled Dive Computer with Heart Rate Monitor, assigned to Johnson Outdoors Inc., the entire teachings and suggestions of which are incorporated herein by reference thereto.
Another physiological data point that may be utilized to improve a diving algorithm is skin temperature. Skin temperature has an influence on a perfusion rate of the diver's body. The perfusion rate of various compartments of a diver's body during a dive will affect transfer of inert gases as well as metabolized oxygen within each compartment. During a typical dive, the perfusion rate determines how the inert gases are solving to tissues in the compartment at higher ambient pressures and dissolving when ambient pressure is decreased. Because the perfusion rate of a diver's skin is affected by skin temperature, a diving algorithm determining decompression parameters that does not take into account skin temperature is inefficient.
Further, a diver's skin forms the largest compartment exposed directly or indirectly to water during a dive. Water conducts heat approximately 20 times better than air, and as a result divers tend to protect themselves from excessive heat loss by wearing thermal isolating suits such as wet and dry suits. In wet suits, the isolation is based on water circulation not directly cooling skin, as a smaller amount of water is trapped between the suit and the skin such that the trapped water is raised in temperature and thereby acts as a buffer to the cooler water outside of the wet suit. In dry suits, the skin protected by the suit is separated from the water by a watertight barrier and body temperature is regulated by thermally protective undergarments.
Regardless of whether a diver utilizes a wet suit or a dry suit, the skin is generally covered. Therefore, dive computers that utilize skin temperature for improving a dive algorithm generally estimate the skin temperature based on surrounding water temperature and diver workload, which is typically estimated from the diver's heart rate or breathing rate.
A better way to determine skin temperature is a direct measurement from the skin of the diver. However, a direct measurement of skin temperature is difficult because a diver's skin is generally covered in order to protect the diver from the cooling effect of the water surrounding the diver's body. Therefore, what is needed is a method and device to directly measure skin temperature of a diver during a dive and provide that measurement data to a dive computer to utilize the skin temperature measurement in a diving algorithm in order to improve the diving experience.
The invention provides such a method and device to directly measure skin temperature of a diver during a dive and provide that measurement data to a dive computer to utilize the skin temperature measurement in a diving algorithm. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.